Orthopedic joint devices of a lower extremity are for example orthoses or prostheses. In particular in the case of prostheses, which replace a natural knee joint, it is advantageous and intended that active influencing of the flexion and extension resistance takes place in the course of the movement cycle, in order to adapt the behavior of the joint device to the movement behavior or to other influences.
In addition, there are motor-driven prostheses or orthoses, the drive motors of which serve the purpose of executing a flexion or extension of the respective joint device.
WO 2007/025116 A2 describes a prosthetic device with an electronically controlled prosthetic knee with a regenerative braking device. In certain situations, the kinetic energy that exists during walking is converted into electrical energy and stored. In other situations it is provided that the gait is assisted or completely controlled. An electronic control system is provided in order to control the operation of the prosthetic device and distribute electrical energy that is generated. Excess electrical energy can be stored in a storage battery or capacitor and called upon for movement assistance at a suitable point in time. The energy storage devices in the case of prostheses or orthoses are large and heavy, in order to have adequate capacity to allow effective movement assistance to take place. In addition, there is the possibility that the active displacement of the upper part in relation to the lower part by correspondingly powerful drives brings the user into situations over which he or she no longer has control.
EP 439 028 B1 describes a swivel connection between two parts of an orthopedic aid in the form of a polycentric prosthetic knee joint, in the case of which a link member is designed to be variable in length under the effect of an external force. The changing of the length of the link member may be of a spring-elastic form, so that the link member resumes its original length immediately after the external force is reduced or ceases.